The present invention refers to a system for controlling actuators in motor vehicle doors using passive components (resistor, capacitor, coil) in order to produce the control commands for operating a device as a window, and wherein at least one electromotive actuating drive and at least one actuating element (switch, button) are located in the door of the vehicle and a control unit is located in the vehicle itself.
Doors of automotive vehicles can have electromotive actuating drives for the central locking and antitheft securing of the door lock, for the raising and lowering of the windows, and for the displacement of the outside mirror. The corresponding actuating elements are also customarily arranged in the door. These include switches and buttons for the displacement of the windows and outside mirror, as well as lock switches to be operated by the car key. The controlling of the electromotive actuating drives is effected via a central control unit within the vehicle. For this purpose, the control commands given via the actuating elements must be evaluated in the control unit and converted into control commands for the actuator drives.
For this purpose, in addition to the generally two-pole connection between actuator unit and actuating drive it is also necessary to lay the corresponding control lines, this being considered to be too expensive and subject to disturbance.
In order to reduce the expense for the wiring of standard devices, it has already been proposed to transmit the switch signals via bus or multiplex circuits, for which fewer lines are necessary. However, special control devices must be provided in the vehicle doors and they must be connected to the actuating elements so that in this case a true saving is obtained only in connection with the wiring within the vehicle and within the transition region between vehicle and door.
In order to reduce the expense for connecting elements, Federal Republic of Germany OS 37 34 449 proposes a device of the aforementioned type in which the control signals are produced in the manner that discrete points of a series connection of resistors acting as voltage divider are contacted by an actuating element. In this case, aside from the two-pole connection between the central control unit and the actuating drive, two control lines each between each of the actuating elements and the control unit are also required. For each operating unit consisting of actuating drive and actuating element, therefore, four connecting lines of the central control unit must still be laid.